Ultra-short wave high frequency amplifier



Jan. 24, 1939. M. VON ARDENNE ULTRA SHORT WAVE FREQUENCY AMPLIFIER:

Fild Jan. 5, 1935 2 Sheets-Sheet l Jnren/or:

Jan. 24, 1939-. M. VON AR DENNE I ULTRA SHORT WAVEHIGH'FREQUENCYAMPLIFIER Filed Jan. 5, 19:55 2 Shets-Sheet 2 5% in J my 7 0 .0 m an a n/m Jmm se y cc fab. 1 W dfia M 0,

H 11 I in wm wame v r nt 5 Patented Jan. 24, 1939 UNITED STATES PATENTOFFlCE ULTRA-SHORT WAVE HIGH FREQUENCY AMPLIFIER Application January 5,1933, Serial No. 650,305 In Germany January 14, 1932 8 Claims.

It has not been possible heretofore in ultrashort wave broadcastingsystems to supply a large town area on a workable basis with thetransmitter outputs which are capable of being produced in practice.Ultra-short receivers with back-coupled audion' are not sufficient. Lowreserve of power, earthing difliculties and disturbing polarizationeffects upon the mounting of the aerials constitute difficulties of acharacteristic kind for the receivers. Increase in the output of thetransmitter provides merely a gradual improvement. The transmitterswould require to be amplified far beyond the present output in order,with the receiving apparatus hitherto employed, to obtain adequatereception. In this manner the transmission would prove very expensive.

The said difficulties are overcome immediately receivers are availablehaving a greater width of band and increased voltage sensitivity.Greater difiiculties exist in the case of ultra-short wave televisionsystems, in which the band modulation to be transmitted is more than 100times greater than the side band inthe case of ultra-short wavebroadcasting systems In order to avoid inadmissible damping of the outerside bands, it is necessary, therefore, to dispense with the use ofback-coupling improvement.

The necessity of employing circuits which have not been artificiallyimproved leads to a decrease in the voltage sensitivity of the receiver,which from a practical standpoint cannot be compensated at the sendingend by increasing the output.

All of these difliculties may be overcome by the provision of areceiving apparatus which possesses a large width of band with increasedvoltage sensitivity.

The invention relates to the provision of an aperiodic high frequencyamplifier for ultra-short waves possessing the properties referred to,i. e., having with adequate voltage sensitivity a sufficiently largewidth of band. According to the invention, this is accomplished by thefact that departure is made from the course of pure fullaperiodicresistance amplification, which is capable of being performed only withvery high D. C. output, and use made of a so-called semi-aperiodicresistance amplification. This may be accomplished, for example, by thefact that in the anode circuits of the resistance amplifier there areconnected oscillating chokes, i. e., chokes which by reason of theirnatural selfcapacity or by the additional connection of specialcapacities and attenuation resistances possess a resonancecharacteristic of considerable band width. This semi-aperiodic couplingis formed according to the usual resistance-capacity coupling, generallycalled aperiodic coupling. For the normal wave range the use ofamplifiers of 7 this kind has little or no importance, as the wave rangewhich requires to be coped with in the ordinary way is much. greaterthan the band Width of the oscillating choke.

In the ultra-short wave range the condition 10 is different. Due to thecharacteristic absorption and propagation conditions of ultra-shortwaves, merely a range enters into the question for the practical usethereof, which is considerably smaller than an octave, viz., the rangebetween m approximately 6.75 and 7.25 m. wave length.

It is possible in this case to perform a valve coupling through themedium of oscillating chokes, i. e., through the medium ofself-inductions accompanied by suflicient loss resistance, 20 whichresonates at the centre of the wave range, i. e., at approximately 7 m.Wave length, with the valve and connection capacity.

To obtain amplifier units of good efliciency with low consumption ofcurrent and a sufficiently wide frequency band for the waverangeconcerned, it is necessary, in addition to the utilization of a certainresonance effect, to also arrange and assemble the remaining parts andamplifier devices according to certain aspects. In particular it isnecessary to reduce at all points the high frequency resistance and alldetrimental capacities so far as this is possible. For this reason it isnecessary, for example, in addition to the D. C. paths, to provide atall points particularly short, high frequency connections, so that thesingle leads are freed as far as possible from high frequency.Preferably, therefore, the leading-in points for the wires to the valveelectrodes are connected in immediate fashion by condensers with acommon point. In addition high frequency chokes must be connected at allpoints in the leads. Suppression chokes and bridging condensers alsorequire tobe connected in the heating wire.

Particularly important is the use of multi-stage valves, as it ispossible only with multi-stage valves of the best construction tomaintain the self-capacities Within such limits that with a 7 in. waveband the requisite high voltage sensitivity is obtained. Withmulti-stage valves constructed with great care it is possible todiminish the capacitative anode loads to such extent that highamplifying figures are capable of being obtained.

The employment of screening grid systems is useful in order to avoid toa large extent the anode reactions, which naturally at these frequenciesoccur to a greater extent than with longer waves. Upon the assembly ofeach two units with their repeater coupling it should be observed thatthe tuning of the first anode circuit is particularly well accomplished,that the two-stage unit is screened off by metal, and the second anodecircuit arranged outside of the screening system, the latter for thepurpose of avoiding back-couplings.

The coupling between the high frequency multi-stage valves according tothe invention, or with the following rectifier and low frequencyamplifying device, is effected preferably through the medium of atunable oscillating choke coupling, i. e., a coupling which consists ofthe parallel connection of an oscillating choke, a tuning condenser anda damping resistance. The tuning and the damping regulation is necessaryfor compensating unsymmetries and for obtaining the sufficient width ofband. The coupling devices are preferably screened off, in the samemanner as other parts of the entire arrangement, more particularly themulti-stage valves, oscillatory circuits, suppressing chokes and thelike.

For the purpose of obtaining an adequate width of band and a maximumdegree of regularity within this band, it is desirable to construct theoscillating choke so as to be irregular in form. This may be effected insuch fashion for example that the winding elevation of the oscillatingchoke is at its largest on one end, and gradually decreases towards theother end. By means of this arrangement it is accomplished that thedistributed capacities vary at single points of the oscillating choke,so that a sharp resonance is unable to occur. Although it is technicallypossible to so perform the assembly and the arrangement of the amplifiersystems and oscillating chokes that a sufiicient width of band for therequisite wave range is obtained, it may be desirable to provide tuningfor the oscillating choke, either for the purpose of performing ad-J'ustment of the wave band and the band width after completion of thereceiving and amplifying device, or merely for the purpose ofcompensating certain unsymmetrical conditions. This tuning of theoscillating choke may be effected with any means of a known kind, forexample by deformation of the coil by magnetic action on the outside, orby heating by means of eddy current or the like. For example, thewindings of the coil may be secured with a certain tension, which uponheating by eddy current is caused to vary, so that in this manneralteration takes place in the relative position of the windings.Furthermore a capacitative or inductive action may be exerted from theoutside through a window in the screening system. The alteration in thetuning may also take place through a window of this nature by means ofan inductive loading.

The invention will be best understood by reference to the accompanyingdrawings, in which Fig. 1 shows a possible form of embodiment of anamplifier device. In Figs. 2 and 3 the structural arrangement of atwo-stage valve is illustrated by way of example, Fig. 2 being anelevational view partially in section and showing the two systems andFig. 3 the right hand side of the valve. Referring to Fig. 1 there areprovided the two-stage high frequency valves A and B, and the rectifiervalve C, which may be coupled with the additional amplifying means.

Coupled with the grid circuit L1, 01 of the first two-stage valve Athrough the medium of a very small condenser K, approximately in theorder of 1 cm., is the aerial circuit. In the anode circuit of the firstsystem of the two-stage valve A, and also the two-stage valve B, thereare connected oscillating chokes D. Between the anode of the firstsystem and the grid of the second system there are connected therepeater condensers Cu, which are preferably in the order ofapproximately 50 cm. Between the two-stage.

valves A and B and also between the two-stage valve B and the audion Cthere are connected the coupling devices E and F, which consist of thechoke coils L2 and L3, respectively connected with which in parallel arethe tuning capacities C2, or C3 and the damping resistances R2 and R3.At all points in the leads there are connected suppressing chokes D7,and in the heating circuits suppressing chokes DH- Immediately behindthe coupling elements the single leads are connected by means ofcondensers with each other and with the screening means. As disclosed byFig. 1, condensers of this kind are connected immediately behind thegrid circuit L1, C1, at the leading-in point of the screening grid, atthe connection for the oscillating choke, etc,, the same all beingpassed to a common point. For the sake of facilitated illustration thesepoints P1 and P2 are not shown in the drawings as points, but as thicklines, but it is to be observed that in the practical execution thecondensers are connected with one point of the screening system. Thesecondensers are preferably approximately 5,000 cm.

The two systems in one two-stage valve are screened by a screening Wallagainst stray coupling. The lead ZA2 of the anode of the second systemis passed out of the bulb at the top. In this manner the disturbingreactions may be kept very much smaller than in the case of commonpassage through the bottom of the socket. The separate lead-out alsooffers the advantage of ready conduction, with little disturbing capacity, to the next unit or to the rectifier respectively. The screeninggrids are made particularly long, and are formed into an equipotentialarea by a plurality of longitudinal wire connections. The cathodes areproduced according to the latest experience as highly emissive bariumcathodes with indirect heating, and are connected together in theshortest way.l These systems in connection with the two-stage valves,and in particular the size and arrangement and the spacing between theelectrodes, may be executed in different ways, and adapted to theparticular conditions prevailing, more particularly the capacitiesoccurring.

Since the arrangement according to the invention results in a suflicientwidth of band as regards a two-stage valve and a one million periodmodulation band width is quite adequate even for very completetelevision transmission, the connection of a second tuned output circuitand the series connection of a plurality of these systems, asillustrated in the drawings, is quite permissible. The resultinghalf-value width may readily be made in an arrangement of this kindgreater than 10 periods, a value which would seem quite sufficient evenfor very complete form of television transmission.

The structural arrangement of a two-stage valve is disclosed by Fig. 2.The two systems (on the right the first system, on the left the secondsystem) are separated from each other by means the control grids Sh, orSta, and the cathodes K1, or K2. In front of the first system there isarranged the oscillating chpke D, the windings of which are spaced apartto a greater extent at the top than at the bottom. Between the screen Son the one hand and the first valve system and the oscillating choke Don the other hand there are arranged the remaining coupling elements,the coupling condenser Cd and the resistance leak Rgz. The couplingcondenser Cit is connected in immediate fashion with the anode A1. Thelead Z Site from the control grid Stz is con nected with the couplingcondenser Cit and the grid resistance Rgz. The remaining leads are notvparticularly shown, as not being important.

The use of one of these valves in connection with a normal audionprovides in itself the ex pected essential improvement in the receptionwith at the same time simplified operation. In the case of cascadeconnection of a plurality of units particular attention should be paidto mutual balancing-out, because the first stage of a semi-aperiodicamplifier would already take over the rectification, and pass on onlythe desired modulation band.

With the arrangement according to the invention it is possible inpractice with two double valves and oscillatory circuit coupling toproduce an approximately one hundredfold amplification and at the sametime maintain a band width of approximately 500 kilo periods with '7 n1.carrier wave. With the assistance of this new amplifier it isaccordingly possible, even with. low expenditure of energy on the partof the ultra-short wave transmitter, to utilize the same successfullyfor purposes of television, broadcasting and multiple modulation.

I claim:

1. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave amplifier of at least two stages coupled with eachother by means of an anode impedance semiaperiodically tuned for saidwidth of band, a coupling condenser and a grid leak resistance, saidanode impedance being an oscillating choke having a varying pitch ofturn for obtaining nonuniformly distributed capacity thereby producing anatural frequency band in the order of the ultra-short wave and ofsufficient width of band.

2. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave amplifier having at least two stages coupled witheach other by means of an anode impedance semi-aperiodically tuned forsaid width of band, a coupling condenser and a grid leak resistance,said anode impedance being an oscillating choke having a varying pitchof turn for obtaining nonuniformly distributed capacity therebyproducing a natural frequency band in the order of the ultra-short waveand of suificient width of band, additional tuning means for performingadjustment of the wave band and of the band width of said oscillatingcoil and for compensating unsymmetrical conditions.

3. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave amplifier having at least two stages coupled witheach other by means of an anode impedance semi-aperiodically tuned forsaid width of band, a coupling condenser and a grid leak resistance,said anode impedance being an oscillating choke having a varying pitchof turn for obtaining non-uniformly distributed capacity therebyproducing-a natural; feque-nc-y band in the order of the ultra-shortwave and of sufficient width of band, additional: means for performingadjustment of the'wave band and of the band width of said oscillatingcoil and for compensating unsymmetrical conditions by altering thedistance of the turns of said oscillating coil.

4. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave amplifier having at least two stages coupled witheach other by means .of' an anode impedance semiaperiodically tuned for.said width of band, a coupling condenser and a grid leak resistance,said anode impedance being an oscillating choke having a varying pitchof turn for obtaining nonuniformly. distributed capacity therebyproducing a naturalrfrequency band in the order of the ultrashort waveand of suflicient width of band, additional tuning means for performingadjustment of the wave band and of the band width of said oscillatingcoil and for compensating unsymmetrical conditions bridging condensersbeing provided in the cathode connections of said stages for obtainingthe shortest high-frequency paths, one pole of said bridging condensersbeing connected to the screen including said amplifier.

5. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave amplifier having at least two multi-stage tubes,

each of which contains two ultra-short Wave amplifier stages coupledwith each other by means of an anode impedance semi-aperiodically tunedfor said width of band, a coupling condenser and a grid leak resistance,said anode impedance being an oscillating choke having a varying pitch1- of turn for obtaining non-uniformly distributed capacity therebyproducing a natural frequency band in the order of the ultra-short waveand of sufiicient width of band, said multi-stage tubes being coupledwith each other by means of a tuned circuit, a coupling condenser andgrid leak resistance, said tuned circuit consisting of an oscillatingchoke, a tuning condenser: and a damping resistance for producing anatural frequency band of said tuned circuit in the order of theultra-short wave and of sufficient width of band.

6. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave amplifier having at least two multi-stage tubes.each of which contains two ultra-short wave amplifier stages coupledwith each other by means of an anode impedance semi-aperiodically tunedfor said width of band, a coupling condenser and a grid leak resistance,said anode impedance being an oscilating choke having a varying pitch ofturn for obtaining non-uniformly distributed capacity thereby producinga natural frequency band in the order of the ultra-short wave and ofsuflicient width of band, said multi-stage tubes being coupled with eachother by means of a tuned circuit, a coupling condenser and a grid leakresistance, said tuned circuit consisting of an oscillating choke, atuning condenser and a damping resistance for producing a naturalfrequency band of said tuned circuit in the order of the ultra-shortwave and of sufficient width of band, said ultra-short-wave amplifierhaving an enclosing screen and bridging condensers provided in thecathode connections of said stages for obtaining the shortesthigh-frequency paths, one pole of said bridging condensers beingconnected to the screen including said amplifier.

7. In an ultra-short wave receiver for greater width of frequency-band,an ultra-short wave ameach other by means of an anode impedancesemi-aperiodically tuned for said width of band, a coupling condenserand a grid leak resistance, said anode impedance being an oscillatingchoke having a varying pitch of turn for obtaining nonuniformlydistributed capacity thereby produc ing a natural frequency band in theorder of the ultra-short wave and of sufficient width of band,additional means for performing adjustment of the wave band and of theband width of said oscillating coil and for compensating unsymmetricalconditions by altering the distance of the turns of said oscillatingcoil by using electromagnetic forces.

8. In an ultra-short wave: receiver for greater width of frequency-band,an ultra-short wave plifier having at least two stages coupled withamplifier having at least two stages coupled with each other by means ofan anode impedance semi-aperiodically tuned for said width of band, acoupling condenser and a grid leak resistance, said anode impedancebeing an oscillating choke having a varying pitch of turn for obtainingnonuniformly distributed capacity thereby producing a natural frequencyband in the order of the ultra-short wave and of suflicient width ofband, additional means for performing adjustment of the wave band and ofthe band width of said oscillating coil and for compensatingunsymmetrical conditions by altering the distance of the turns of saidoscillating coil by using an additional heating effect, causing changeof the op 15 erative length of said coil.

MANFRED VON ARDENNE.

